1. Field of the Invention
This invention relates to catalysts which are useful as hydrogenation catalysts and particularly for the catalytic hydrogenation of aldehydes, ketones, carboxylic acids, carboxylic acid esters and nitroaromatic compounds. This invention also relates to processes for preparing said catalysts and to hydrogenation processes using said catalysts.
2. Description of Related Art
Hydrogenation reactions and catalysts useful in such reactions are well known. For example, U.S. Pat. No. 4,666,879 describes an extruded copper chromite-alumina catalyst prepared by blending together from 40-82% by weight of copper chromite and 18-60% of an extrudable alumina, typically having a pseudoboehmite or a hydroxy boehmite structure. The extruded catalyst after calcining is useful for the liquid and vapor phase hydrogenation and hydrogenolysis of various carbonyl compounds and the functional side groups of aromatic compounds. The extruded catalyst is characterized as having a surface area of between 20 and 225 square meters per gram and a packed apparent bulk density of between about 0.70 and about 1.20 g/cc.
U.S. Pat. No. 4,762,817 describes an aldehyde hydrogenation catalyst consisting essentially of a mixture of copper and zinc oxide impregnated with a minor selectivity improving amount of a selectivity enhancer comprising the combination of an alkali metal selectivity enhancer selected from the group consisting of sodium, potassium, lithium, cesium, and mixtures thereof and a transition metal selectivity enhancer selected from the group consisting of nickel, cobalt, and mixtures thereof.
U.S. Pat. No. 4,929,771 describes catalyst compositions comprised of chemically-mixed, copper-titanium oxides and the use of such catalyst compositions in the hydrogenation of certain esters to obtain the alcohol corresponding to the acid residue of the ester.
U.S. Pat. No. 5,008,235 describes a process for hydrogenating feeds into their corresponding alcohols by contact with a coprecipitated catalyst comprising copper, aluminum, and a metal (X) selected from the group consisting of magnesium, zinc, titanium, zirconium, tin, nickel, cobalt and mixtures thereof; that has been reduced with an increasing temperature during the reduction.
U.S. Pat. No. 5,043,509 describes catalyst particles employed in reactions involving the conversion of organic compounds that should possess a desired configuration in order to maintain a desired voidage which will permit passage of the feedstock through the catalyst bed during the conversion reaction. Solid phosphoric acid catalysts which comprise an admixture of an acid of phosphorus and a solid binder such as a siliceous material may be formed into polylobular, tubular, ridged, fluted, or channeled cylindrical particles which will permit a sufficient amount of voidage in the catalyst bed to be maintained even though the catalyst particles will swell during the reaction due to the formation of coke on the surface thereof.
U.S. Pat. No. 5,093,534 describes a process for the preparation of saturated alcohols from aldehydes. The hydrogenation of saturated and unsaturated aldehydes to alcohols can be carried out over catalysts containing copper and nickel. In this process, the selectivity of the alcohol preparation is further improved by a combination of an alkaline copper catalyst and a nickel-containing catalyst whose carrier material has acidic centers of a certain acid strength H.sub.o.
U.S. Pat. No. 5,124,295 describes to a formed copper chromite catalyst prepared from a blend comprising from about 20 to about 80% by weight of copper chromite and from about 20 to about 80% by weight of at least one extrudable inorganic binder material wherein the catalyst has a surface area of from about 20 to about 225 m.sup.2 /g, and the total pore volume of the pores in said catalyst having a diameter of up to about 95,000 A is between about 0.35 to about 1 cc/g. In another embodiment, the patent describes a process for preparing this formed copper chromite catalyst and the process comprises:
(A) preparing a blend comprising from about 20 to about 80% by weight of copper chromite, from about 20 to about 80% by weight of at least one extrudable inorganic binder material, from about 1 to about 10% by weight, based on the weight of the binder, of a peptizing agent, and sufficient water to form an extrudable blend; PA1 (B) extruding the blend to form an extrudate; and PA1 (C) calcining the extrudate. This patent also describes a process for hydrogenating aldehydes, ketones, carboxylic acids and carboxylic acid esters with catalysts of the type described. PA1 (A) simultaneously and separately adding to a first vessel, (1) a first aqueous solution comprising a copper zinc salt; (2) a second aqueous solution comprising a soluble base, provided that either the copper solution or the soluble base solution also contains a soluble salt of at least one second metal; or (3) a third aqueous solution comprising a soluble salt of at least one second metal is added simultaneously to the first vessel whereby an aqueous slurry of insoluble solid is formed in the first vessel, provided further that the second metal is chromium, molybdenum, tungsten, or vanadium; PA1 (B) advancing at least a portion of the aqueous slurry from the first vessel to a second vessel; PA1 (C) recovering the solids from the aqueous slurry in the second vessel; and PA1 (D) calcining the recovered solids. PA1 (A) preparing a first aqueous solution containing at least one water-soluble copper salt, at least one water-soluble iron salt, and at least one water-soluble manganese salt; PA1 (B) preparing a second solution containing at least one water-soluble basic aluminum salt and at least one alkaline precipitating agent; PA1 (C) mixing the first and second solutions wherein an insoluble solid is formed; PA1 (D) recovering the soluble solid; and PA1 (E) calcining the recovered solid to form the desired catalyst. Also described is a process for hydrogenating aldehydes, ketones, carboxylic acids and carboxylic acid esters. PA1 (A) preparing a first aqueous solution containing at least one water-soluble copper salt and at least one water-soluble zinc salt; PA1 (B) preparing a second solution containing at least one water-soluble basic aluminum salt and at least one alkaline precipitating agent; PA1 (C) mixing the first and second solutions whereby an insoluble solid is formed; PA1 (D) recovering the insoluble solid. Also described is a process for hydrogenating aldehydes, ketones, carboxylic acids and carboxylic acid esters with catalysts of the type described.
U.S. Pat. No. 5,134,108 describes a hydrogenation catalyst comprising a major amount of the oxides of a first metal selected from copper or zinc, a second metal selected from chromium, molybdenum, tungsten and vanadium, and optionally, a minor amount of the oxide of a promoter metal selected from the group consisting of manganese, barium, zinc, nickel, cobalt, cadmium, iron and any combination thereof provided that the promotor metal is not zinc if the first metal is zinc. The average particle diameter of the powder is from about 6 to about 20 microns; and the particle surface area is from about 20 to about 70 m.sub.2 /g. The process for preparing this catalyst is described as comprising the steps of
U.S. Pat. No. 5,155,086 describes a catalyst in powdered form comprising the oxides of copper, iron, aluminum and manganese wherein the atomic ratio of copper to iron is at least 1:1 and a process for preparing such hydrogenation catalysts which comprises the steps of
U.S. Pat. No. 5,345,005 describes a catalyst in powdered from which comprises a major amount of the oxides of copper and zinc, and a minor amount of aluminum oxide wherein the pore volume of pores of said catalysts having a diameter between about 120 and about 1000 A is at least about 40% of the total pore volume and a process for preparing hydrogenation catalysts comprising the oxides of copper, zinc and aluminum which comprises the steps of
There is still a need, however, for shaped chromium-free hydrogenation catalysts that have high catalytic activity which are strong and acid resistant.